Thin-film coils used in creating magnetic fields in semi-conductor devices are generally used in connection with magnetic field sensors.
For example, U.S. Pat. No. 5,319,158 (Lee et al.) relates to a semi-conductor device with an integrated coil. The coil may provide a strong magnetic field with a relatively good homogeneity. On the other hand, low power consumption is required, especially when the coil is integrated in a semiconductor assembly or a mobile device.
There are single winding thin-film coils that may provide electromagnetic field of a relatively good homogeneity. But in order to achieve a strong intensity of the field, it may be necessary to drive these single winding thin-film coils with a high current.
There are also known thin-film coils with multiple windings in a single layer. For example, U.S. patent application Ser. No. 2004/0130323 describes an electromagnetic field sensor having such a single layer coil with multiple windings.
These thin-film coils may be produced by any known thin-film technologies such as, for example, by forming a spiral shaped conductive layer on a substrate. The electromagnetic field generated by such thin-film coils may increase with the number of windings so that power consumption may decrease. On the other hand, since the windings have to be spaced apart from each other in a horizontal direction, the gaps between neighboring windings may cause the homogeneity of the generated electromagnetic field to decrease. Therefore a single layered thin-film coil with a large number of windings may not be able to produce a strong electromagnetic field with a relatively good homogeneity.